1. Field of the Invention
This invention pertains to the art of fuel injector nozzle assemblies and more particularly to a rotating micro nozzle assembly having an integrated premixing chamber.
2. Description of the Related Art
In a combustion apparatus such as an engine, fuel distribution in the combustion chamber is an important factor relating to optimization of the combustion process.
Fuel injection nozzles used in present day combustion engines suffer from limited spray angle. For instance, fuel spray patterns are typically constrained to cone angles of less than 90 degrees, leading to combustion instabilities caused by non-uniform temperature distribution within the engine. This non-uniformity causes inefficient fuel combustion leading to emission of undesired combustion products. As a result, many nozzles are used to cover a wide area in an attempt to provide efficient fuel burning.
Some existing fluid delivery systems attempt to provide more optimal fuel distribution through the generation of smaller size droplets that provide a larger surface area for improved combustion. Nozzles with multiple holes and/or swirlers or air/fuel pre-mix capabilities are known in the art.
However, there is still a need in the art for improvement in uniform temperature distribution in the combustion chamber as well as reduced system complexity.
Microelectromechanical systems (MEMS) are being used in a wide variety of applications. The present invention is directed to a MEMS-based spinning nozzle that addresses the needs in the art of fuel injectors.
The present invention provides a spinning micro nozzle mechanism with an integrated premixing chamber.
It is a primary object of the present invention to provide a micro nozzle assembly having a rotatable nozzle for providing atomized fuel to a combustion chamber.
It is a further object of the invention to provide a nozzle body having components formed by an etching process in silicon carbide.
It is a further object of the invention to provide a method of assembling a nozzle assembly having an integrated premix chamber and a rotatable nozzle member.
In the present invention, there is provided a nozzle assembly adapted to deliver fuel from an associated supply source to an associated combustion chamber. The nozzle assembly comprises a rotatable nozzle body having a first flange surface and including a supply passage aligned on a main axis thereof, the rotatable nozzle body being adapted for rotation about the main axis and defining an internal fuel distribution cavity in flow communication with the supply passage. The rotatable member further defines a curvilinear fuel delivery channel in flow communication with the internal fuel distribution cavity disposed in a plane generally perpendicular to the main axis. The curvilinear fuel delivery channel has an outlet opening through an exterior surface of the nozzle body. The nozzle assembly further includes substrate means having a bore aligned on the main axis for rotatably supporting the nozzle body. The substrate means includes a first seating surface for seating the flange surface.
According to one aspect of the invention, the nozzle assembly further comprises means carried on the substrate for premixing fuel from the associated supply source, wherein the premixing means are operative to deliver the fuel to the supply passage.
According to another aspect of the invention the nozzle assembly further includes means carried on the substrate for providing pressurized air to the associated combustion chamber, wherein the air providing means are operative to direct a stream of air past the outlet.
According to another aspect of the invention, the nozzle body comprises a spacer member having a hollow cylindrical body having first and second ends, wherein the supply passage is defined by an internal surface thereof; an anchor member fixedly secured to the first end of the spacer member, wherein the anchor member encompasses the first flange surface; and, a base member fixedly secured to the second end of the spacer member, wherein the base member encompasses the internal fuel distribution cavity and the curvilinear fuel delivery channel.
According to another aspect of the invention, the base member comprises a first body portion affixed to the spacer member; and, a second body portion affixed to said first body portion; wherein said first body portion and said second body portion cooperate to form said internal fuel distribution cavity and said curvilinear fuel delivery channel.
According to another aspect of the invention, the first body portion comprises a planar surface having an open cavity formed therein and an open curvilinear channel communicating with the cavity and extending through an exterior surface of the first body portion; and the second body portion has a planar surface abutting the planar surface of the first body portion to cap the open cavity and the open curvilinear channel.
According to another aspect of the invention, there is provided a method for forming a nozzle assembly comprising the steps of providing a substrate having first and second surfaces and a bore extending therebetween; providing a spacer member having a hollow cylindrical body, first and second ends, and an internal surface defining a supply passage aligned on an axis thereof; providing an anchor member having a flange surface adapted to seat on the first surface of the substrate; providing a base member defining an internal fuel distribution cavity and at least one curvilinear fuel delivery channel in flow communication with the internal distribution cavity, the curvilinear fuel delivery channel extending through an exterior surface of the base member to define an outlet; inserting the spacer member through the substrate bore; affixing the anchor member to the first end of the spacer member; seating the flange surface on the first surface of the substrate; and affixing the base member to the second end of the spacer member.
According to another aspect of the invention, the step of providing a base member further includes the steps of providing a first body portion comprising silicon carbide having a planar surface; etching first body portion to form an open cavity in the planar surface and an open curvilinear passage communicating with the cavity, wherein the curvilinear passage extends through an exterior surface of the first body portion; and providing a second body portion having a planar surface; and bonding said planar surface of said second body portion to said planar surface of said first body portion to form said base member.
One advantage of the present invention is the improved spray angle achieved by the rotating nozzle member.
Another advantage of the present invention is the increased atomization of the fuel.
Another advantage of the present invention is the integrated premixing chamber allows further miniaturization of the nozzle assembly.
Another advantage of the present invention is that batch fabrication and batch assembly of the nozzle components reduces the cost.
Another advantage of the present invention is the reduction in number of components compared with other prior art nozzle assemblies.
Another advantage of the present invention is the use of silicon carbide allows the nozzle assembly to operate at higher temperatures than conventional systems.
Another advantage of the present invention is that the increase atomization of the fuel, due to the nozzle design and operation, provides for a reduction in the necessary pressure as compared to conventional systems.
Still other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification.